This invention relates generally to package wrapping machines utilizing thin, stretchable film to wrap and display articles contained in trays and, more particularly, to a film monitoring system for detecting the expiration or breakage of a continuous film source and for stopping the machine in response to the detection of such film conditions.
A variety of film wrapping machines are known in the prior art. These machines provide for wrapping packages with thin, stretchable film in any one of a variety of ways. The film may be fed into the wrapping machine from the top, bottom or side of the machine and oftentimes is not readily visible to the operator of the wrapping machine.
In many of the wrapping machines there is also a potential for contamination of the machine from packages to be wrapped. For example, if an open tray of ground meat is to be wrapped and the film supply has expired or broken, the package is transported through the wrapping machine with no film covering the open tray. Even though such contamination may not require immediate attention by the machine operator, such contamination can increase the frequency of necessary machine cleaning and maintenance, thus increasing the inoperable down time of the wrapping machine. Furthermore, an inattentative operator may have to retrieve a group of packages which have been run through the machine but have not been wrapped due to a failure of the film source.
It is, thus, apparent that the need exists for a film source monitoring system to sense breaks or expiration of a film source for a film wrapping machine and to stop the machine until such film problems have been corrected.